1. Field of the Invention
This invention relates to an optical type scanning microscope. This invention particularly relates to a scanning microscope, wherein an optical means, which irradiates a light beam to a sample, is moved with respect to a sample supporting member, on which the sample is supported, such that the light beam may scan the sample. This invention also relates to a novel scanning mechanism.
2. Description of the Prior Art
Optical type scanning microscopes have heretofore been used. With the scanning microscope, a light beam is converged to a small beam spot on a sample, and the sample is two-dimensionally scanned with the beam spot. The light beam, which has passed through the sample during the scanning, the light beam, which has been reflected from the sample during the scanning, or the fluorescence, which is produced by the sample during the scanning, is detected by a photodetector. An enlarged image of the sample is thereby obtained.
Basically, the scanning microscope comprises:
i) a light source which produces a light beam, PA0 ii) a sample supporting member on which a sample is supported, PA0 iii) a light projecting optical means with which an image of the light beam is formed as a small beam spot on the sample, PA0 iv) a light receiving optical means with which the light beam radiated out of the sample (i.e. the light beam, which has passed through the sample, the light beam, which has been reflected from the sample, or the fluorescence produced by the sample) is condensed, and an image of the condensed light beam is formed as a point image, PA0 v) a photodetector which detects the point image, and PA0 vi) scanning mechanism for two-dimensionally scanning the sample with the beam spot. An example of the scanning microscope is disclosed in Japanese Unexamined Patent Publication No. 62(1987)-217218. PA0 i) a sample supporting member on which a sample is supported, PA0 ii) a light source which produces a light beam, PA0 iii) a light projecting optical means with which an image of said light beam is formed as a small beam spot on said sample, PA0 iv) a light receiving optical means with which the light radiated out of said sample is condensed, and an image of the condensed light is formed as a point image, PA0 v) a photodetector which detects said point image, PA0 vi) a movable member which supports at least part of said light projecting optical means and at least part of said light receiving optical means together, and PA0 vii) a drive means which reciprocally moves said movable member such that said beam spot may scan said sample in a one-dimensional scanning direction, PA0 a) a collimating optical means for collimating said light beam, which has been produced by said light source, on the side outward from said movable member and guiding the collimated light beam to a direction parallel to said scanning direction, and PA0 b) a mirror, which is secured to said movable member and which reflects said collimated light beam towards said sample supporting member. PA0 1) a mirror for reflecting the light, which has been radiated out of said sample, to a direction parallel to said scanning direction, and PA0 2) a collimating optical means for collimating the light, which has been reflected by said mirror of said light receiving optical means. PA0 i) a material supporting member on which a material to be scanned is supported, PA0 ii) a light source which produces a light beam, PA0 iii) a light projecting optical means with which an image of said light beam is formed as a small beam spot on said material, PA0 iv) a light receiving optical means with which the light radiated out of said material is condensed, and an image of the condensed light is formed as a point image, PA0 v) a photodetector which detects said point image, PA0 vi) a movable member which supports at least part of said light projecting optical means and at least part of said light receiving optical means together, and PA0 vii) a drive means which reciprocally moves said movable member such that said beam spot may scan said material in a one dimensional scanning direction, PA0 a) a collimating optical means for collimating said light beam, which has been produced by said light source, on the side outward from said movable member and guiding the collimated light beam to a direction parallel to said scanning direction, and PA0 b) a mirror, which is secured to said movable member and which reflects said collimated light beam towards said material supporting member. PA0 1) a mirror for reflecting the light, which has been radiated out of said material, to a direction parallel to said scanning direction, and PA0 2) a collimating optical means for collimating the light, which has been reflected by said mirror of said light receiving optical means.
In the conventional optical type scanning microscopes, a mechanism which two-dimensionally deflects a light beam by a light deflector is primarily employed as the scanning mechanism.
However, the scanning mechanism described above has the drawback in that a light deflector, such as a galvanometer mirror or an acousto-optic light deflector (hereinafter referred to as "AOD"), which is expensive, must be used. Also, with the scanning mechanism described above, a light beam is deflected by a light deflector. As a result, the angle of incidence of the deflected light beam upon an objective lens of the light projecting optical means changes momentarily, and aberration is caused to occur. Therefore, the scanning mechanism described above also has the problem in that it is difficult for the objective lens to be designed such that aberration can be eliminated. Particularly, in cases where an AOD is utilized, astigmatism occurs in the light beam radiated out of the AOD. Therefore, in such cases, a special correction lens must be used, and the optical means cannot be kept simple.
In order to eliminate the aforesaid problems, a scanning mechanism has heretofore been proposed wherein a light beam is not deflected but a sample is scanned with the beam spot of the light beam. For example, in U.S. patent application No. 5,081,350, a novel mechanism has been proposed wherein a light projecting optical means and a light receiving optical means are supported on a single movable member, the movable member is moved reciprocally with respect to a sample supporting member, and a beam spot of a light beam is thereby caused to scan a sample.
In such cases, for the purpose of achieving quick scanning, it is advantageous that the light source for producing a light beam to be irradiated to the sample is located on the side outward from the movable member, and the movable member is thereby made light in weight. When the light source for producing a light beam to be irradiated to the sample is thus located on the side outward from the movable member, it is necessary for a means to be utilized for guiding the light beam to part of the light projecting optical means located in the region inside of the movable member. As the means for guiding the light beam to part of the light projecting optical means located in the region inside of the movable member, an optical fiber may be utilized as disclosed in, for example, U.S. Pat. No. 5,081,350.
However, in cases where an optical fiber is utilized as the means for guiding the light beam to part of the light projecting optical means located in the region inside of the movable member, the optical fiber bends as the movable member moves reciprocally, and therefore the amount of the light beam guided through the optical fiber often fluctuates. Also, the amount of the light beam guided through the optical fiber often fluctuates due to vibrations of a fiber coupling, or the like. If the amount of the light beam guided through the optical fiber fluctuates, nonuniformity will occur in a microscope image which is formed by the scanning microscope.